1. Field of the Invention
The present invention relates to a novel activated human antigen-presenting cell, a method for activating a human antigen-presenting cell in vitro, a method for treating cancer and infectious diseases including AIDS using the activated human antigen-presenting cell, and a use of the activated human antigen-presenting cell in preparing medicines for such treatment.
2. Disclosure of Related Art
There have been various strategies for the therapeutical treatment of cancer patients, including surgical extraction of tumor foci, chemotherapy, radiotherapy and immunotherapy. However, the cure rates of these strategies are not as high as they are expected. Therefore, there exists a strong demand for developing new therapeutic agents and methods which can provide improved cure rates in the treatment of cancer. Macrophages, B cells and dendritic cells, which are members of antigen-presenting cell (APC), have been known to be cells essential for immune response. Recently, an idea that using APCs, particularly dendritic cells, to induce cancer immunity may be effective in treating cancer (Grabbe, S. et al., 1995, Immunol. Today, 16, 117) has attracted much attention.
Several processes for preparing dendritic cells from mouse have been known, such as from the spleen (Clowley, M. et al., 1989, Cell. Immunol., 118, 108), from the bone marrow (Inaba, K. et al., 1992, J. Exp. Med., 176, 1693) and from the epidermis (the epidermis-derived dendritic cells are known as “Langerhans's cells) (Witmer-Pack, M. et al., 1987, J. Exp. Med., 166, 1487). Furthermore, it was demonstrated that pulsing the dendritic cells prepared from the murine bone marrow with tumor antigen and administrating the pulsed dendritic cells into a subject prior to and after the implantation of tumor cells into the subject can elicit tumor immunity (Celluzzi, C. M. et al., 1996, J. Exp. Med., 183, 283; Paglia, P. et al., 1996, J. Exp. Med., 183, 317)
The following processes are known for preparing human APCs, particularly dendritic cells, from peripheral blood or umbilical cord blood: a process in which FcR+ cells, T cells, B cells and NK cells are removed from human peripheral blood using the antibodies against them from peripheral blood monocytes to give APCs (Hsu et al., 1996, Nature Med., 2, 52); and a process in which adherent cells in human peripheral blood monocytes from which CD19+ B cells and CD2+ T cells were removed are cultured with a granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin 4 (IL-4) for about one week (Sallusto, F. et al., 1994, J. Exp. Med., 179, 1109). It has been reported that such human peripheral blood-derived APCs have both allogeneic and autologous MLR (mixed leukocyte reaction) enhancing effects. On the other hand, for preparing APCs from human umbilical cord blood or bone marrow cells, a process is known where GM-CSF and tumor necrosis factor-α (TNF-α) are used to prepare APCs from CD34+ cells found in umbilical cord blood or bone marrow (Santiago-Schwartz, F. et al., 1992, J. Leukocyte Biol., 52, 274; Caux, C. et al., 1992, Nature, 360, 258). However, although the APCs prepared from human umbilical cord blood or bone marrow cells by such a process as mentioned above have an allogeneic MLR enhancing effect, they have no (Santiago-Schwartz, F. et al.) or, if any, extremely poor (Caux et al.) antologous MLR enhancing effect.
Recently, it has been demonstrated that a therapy with the APCs that had been pulsed with tumor antigens is effective for treating B cell lymphoma patients (Hsu, F. J. et al., 1996, Nature Med., 2, 52). That is, a therapy for B cell lymphoma patients was successfully achieved by culturing APCs prepared from peripheral blood of a B cell lymphoma patient together with B cell lymphoma antigens in vitro and administrating the cultured APCs into the B cell lymphoma patient.
As shown in this exemplary therapy, methods in which APCs are pulsed with tumor antigens may be very effective for treating cancer if the cancer can be clearly identified by their tumor antigens, like B cell lymphoma. However, such methods as mentioned above take enormous time and costs, because the tumor antigens are generally specific to the individual patients and, therefore, must be specified for the respective patients, and the specified tumor antigens must be produced in large quantities to pulse the APCs. Furthermore, since it is impossible for most of the cancer patients to identify their tumor antigens, the range of application of the method in which APCs are pulsed with tumor antigens is limited. In view of the above, in order to apply the therapy with APCs (hereinafter referred to as “the APC therapy”) recognized to be a very effective therapy for cancer, to as many patients as possible, there has been a strong demand for development of a method for preparing human APCs effective for treating cancer without the aid of tumor antigens.
Within a living body, various types of β-galactosylceramides and β-glucosylceramides are present, each of which has a sugar linked to a ceramide via a β-linkage (Svennerholm, L. et al., 1972, Biochem. Biophys. Acta., 280, 626; Karlsson, K. A. et al., 1973, Biochim. Biophys. Acta., 316, 317). On the other hand, the inventors have found that α-galactosylceramides have remarkable immunostimulatory properties and anti-tumor properties (Morita, M. et al., 1995, J. Med. Chem., 38, 2176), and that such properties of α-galactosylceramides and α-glucosylceramides are far more potent than those of the corresponding β-anomers (Motoki, K. et al., 1995, Biol. Pharm. Bull., 18, 1487). It was also found that compounds having an α-glycosylceramide structure show a protecting effect against radiation when administered into a living subject (Motoki, K. et al., 1995, Bioorg. Med. Chem. Lett., 5, 2413) and cause an increase in the number of platelets and white blood cells (Motoki, K. et al., 1996, Biol. Pharm. Bull., 19, 952). The inventors also have found that an α-galactosylceramide, KRN7000, can enhance the functions of dendritic cell-rich APCs prepared from the murine spleen, and that the enhanced APCs exhibit an anti-tumor effect when administered into a subject before tumors are implanted into the subject (Koezuka, Y. et al., 1995, The 9th International Congress of Immunology, Abstract, 55; Yamaguchi, Y. et al., 1996, Oncol. Res. 8, 399).
However, the effect of glycoside compounds, such as KRN7000, or salts thereof on APCs rich in dendritic cells from murine bone marrows and Langerhans's cells from murine epidermis has not been clarified. In addition, there is no report on anti-tumor effects of the APCs rich in murine spleen- and bone marrow-derived dendritic cells, which have been stimulated with KRN7000, upon administration into a subject after tumors are implanted into the subject. No effect of glycoside compounds such as KRN7000 or salts thereof on human APCs has also been known.
To address the above-mentioned demands, the present invention provides a novel human APC activating agent which is useful in preparing activated human APCs that exhibit a sufficient therapeutic effect on cancer and various infectious diseases including AIDS without the need to pulse the antigen-presenting cells with tumor antigens, and also provides a method for activating human APCs with such an activating agent.